Gridded Normalized Difference Vegetation Index of SLSTR/S3A

In the ‘LST_ancillary_ds.nc ‘(Level 2 product of SLSTR ), was the NDVI data calculated using surface reflectance of TOA reflectance?

Thanks a lot in advance.

On the page https://sentinel.esa.int I couldn’t quickly find an answer.
I would suggest that you write a mail to EOSupport@copernicus.esa.int.
It is the official contact point for such questions.
If you get an answer, please let us know.